With reference being initially made to FIG. 1 of the drawings, apparatus conventionally employed in taking blood samples from a patient's artery is shown. More particularly, a flexible plastic catheter 1, which is adapted to removably house a needle cannula 2 when axially disposed therein, is adapted to be inserted within the patient's artery. As is conventional, the proximal end of the needle cannula projects beyond the proximal end of the catheter 1 to permit the puncturing of the artery wall with the cannula while housed in the catheter. The proximal end 3 of the catheter 1 is tapered inwardly toward the proximate end of the cannula so as to facilitate the entry of the catheter into the artery wall aperture formed by the needle cannula.
The distal end of the catheter 1 has a fitting 4 fixedly secured thereto. As is known, the fitting has an axially extending aperture, not shown, so as to fluidically communicate with catheter 1. The head of the fitting 4 has a bead 5 which is adapted to threadedly mate with an internally threaded cap of a sealing stylet (not shown), or alternatively, with an internally threaded tubular end portion of a syringe (not shown).
In a well known manner, when it is desired to take multiple blood samples from a patient, the catheter-cannula assembly is initially inserted into the patient's artery, and subsequently, the needle cannula is removed from the catheter with the latter remaining within the patient's artery. In the instance that a blood sample is in fact ready to be taken, the syringe must be immediately attached to the catheter fitting 4 in order to prevent a substantial amount of blood from issuing out of the catheter. When the desired amount of blood has been deposited within the syringe, the same is disengaged from catheter fitting 4, and a sealing stylet is immediately axially inserted within catheter 1 so as to again prevent blood from issuing out of catheter 1. When another blood sample is desired, the stylet is removed from catheter 1, and in order to prevent a substantial amount of blood from issuing out of catheter 1, a new syringe must immediately be engaged with catheter fitting 4.
As can be readily appreciated from the foregoing description of a conventional blood sampling procedure, the same is quite harried and somewhat difficult to perform in accordance with clinically accepted practices. A need therefore exists for the development of apparatus which will substantially simplify blood sampling procedures and render the same more immaculate.